Ratio varying device



NGV. 19, 1940. H. ZIEBOLZ ET AL 2,222,551

RAT IO VARYING DEVI CE Filed Oct. 29, 1936 3 Sheets-Sheet l Nov. 19, 1940. H. zxEBoLz ErAL RATIO VARYING DEVICE Filed Oct. 29, 1936 3 Sheets-Sheet 2 NOV. 19, 1940. H, Z|EBOLZ ET AL 2,222,551

RATIO VARYING DEVICE Filed Oct. 29, 1936 5 Sheets-Sheet 5 measuring apparatus relays and the like.

Patented Nov. 19,

UNITED STATES PATENT OFFICE RATIO VABYING DEVICE Herbert Ziebolz and Hubert J. Velten, Chicago, Ill., assignors to Askania Regulator Company, Chicago, Ill., a corporation of Illinois Application October 29, 1936, Serial No. 108,298

6 Claims.

for measuring and/,or controlling physical conditions.

'I'he invention aims to provide a. novel, simple and reliable mechanism for varying the magnitude of movements and/or forces in accordance to the product of a plurality of factors, hereinafter referred to as "correction factors.

Other aims and advantages of this invention will appear in the following description, considered in connection with the accompanying drawings wherein: y

Figure 1 is a diagrammatic illustration of one form of mechanism for practicing the invention.

Figure 2 is a table and chart illustrating the mechanical operation of the mechanism shown in Figure 1.

Figure 3 is a diagrammatic illustration of the invention as applied to a measuring device.

Figure 4 is a diagrammatic illustration of the invention as applied to a regulating device.

Figure 5 is the dial and pointer of .the setting device of Figure 4 in larger scale.

Figure 6 is a modified form of the dial and pointer.

Referring to Figure 1, showing diagrammatically one form of the invention, a lever I0; pivotally mounted at II, is acted upon by a force A indicated by an arrow I2. A second lever I3 pivotally mounted at Il extends substantially parallel to the first lever I0 and is acted upon by a force B, acting in opposition to the force A. The force B is indicated by an arrow I5. A connecting member or ratio slider shown as having the form of a prism I6 secured to a rod I1 is interposed between the levers yI0 and I3 to transmit forces or movements from one to the other. The ratio of the forces A and B may be varied by moving the rod I'I in axial direction. The rod and prism effecting the change of leverage will be called in the following ratio slider.

The mechanism, so far as described, is known in the art, and used, for example, to transmit controlling impulses, such as forces or movements, to In that particular application the controlling impulse may be applied at A and the measuring' apparatus, or relay, be operated by the second lever I3, for example, by connecting it to the same at B. By means of the ratio slider it is therefore possible to vary the magnitude o f .an impulse A with regard to an apparatus connected to the impulse transmitting lever I3 at B by varying the leverage of the mechanism. A displacement of the ratio slider, in effect, multiplies the impulse A with a correction factor."

For many purposes, however, the introduction of only one correction factor is insufficient. The present invention permits the introduction of the product of a plurality of correction'factors and is based on a discovery which will now be described.

The characteristic of the mechanism can be mathematically expressed as follows:

A R +21 where:

R-Ratio of the forces or lever arms A a R= c-Distance of the points of application of the forces A and B from Ithe pivot points; y--Displacement of the ratio slider, positive to the right, negative to the left.

The Equation (A) can be transformed to read in terms of y, as follows:

It was found that for values of R ranging between about .5 and 2.0 the Equation (E) may be substituted with close approximation by the following equation:

where:

K-an arbitrary constant depending upon the constructional design of the mechanism.

y=K log R;

A second series oi displacement valuta ya appears in the tablein Figure 2 based on the Equation (F) which in this specific example assumes the form:

(H) #2-56.78 (10g R) The constant K=56.78 is determined as follows: 'I'he Equation (F) comprises a family of logarithmic curves. all of which go through the point R=1; y=0. From this family one curve is selected which has at least two points in common with the 1li-curve. In this case the point R=l.5; 111:10 of the 1li-curve was taken to determine the constant in the equation of the 11a-curve. From (F) follows:

y- (J) K log R From the above Equation (H) the values of y: for the values of R in the table are calculated and are entered under yl values. A comparison of the 1,11 values with the ya values in the table shows that within the above-mentioned range the Equation (F) can be' substituted with close approximation for Equation (E).

If now for example the known arrangement is to be employed for mechanical multiplication, then in a simple case where p and q are two factors to be multiplied. Now

log R=log p-I-log q and consequently from Equation (F) y=K (log p-i-log q) Therefore, the displacement y of the slider I3 is equal to the sum of the logarithms of the two factors to be multiplied. It follows that the transmission ratio varies with the product of those factors the logarithms of which are algebraically applied to the slider I3. If the logarithms of the two factors to be multiplied are summed geometrically then the transmission ratio gives the product. if they are subtracted geometrically, then the transmission ratio gives the quotient.

According to the present invention the rod I1 of the ratio slider is connected to a mechanical adding device, shown as being a double armed lever or summarizing member I3 pivotally connected to the rod I1 at I9, and displaceable by means of adjustment sliders 23 and 2I. The adjustment sliders are provided with pointers 22 and 23 corresponding with logarithmically calibrated scales 24 and 23. The rod Il will upon displacement of the adjustment sliders be moved by the arithmetic sum of the displacements.

The sum of the displacements may be read by means of a pointer 23 and scale 21 of the rod Il. It is obvious that three and more logarithmic correction factors may be introduced in the same manner or by means of other adding devices well known in the art.

A device for automatically introducing two correction factors is shown in Figure 3 in which the invention is shown as applied to gas meters.

While the movement of the movable members, the levers I0 and I3 of Fig. 1 is restricted to relatively small deflections. the movable members of Fig. 3, the disks 33 and 31. may be regarded as levers having an unlimited range of movement, the lever axes being 32 and 33 and the effective lever arms the distances between the axes and the friction wheel.

A volumetric gas meter gives a correct reading only under normal temperature and pressure conditions. A rise in pressure above, or a drop in temperature below the normal value will allow a greater weight of gas to pass through the meter than is indicated by the same and vice versa. In other words, the weight of gas per volume unit may vary without aifecting the reading of the meter.

Referring to Figure 3 a flow of gas carried by a conduit 33 passes through a volumetric meter 3i. A rotating shaft 32 for operating the indicating mechanism of the meter is shown as extending from the meter. The shaft 32 carries a disk 33 driving a friction wheel or ratio slider 34 rotatably mounted at 33 on an axially movable shaft 33. 'Ihe friction wheel, in turn, moves a second disk 31 on a shaft 33 operating the indicating mechanism of the meter shown as a revolution indicator 33 reading in terms of standard conditions. As shown in Fig. 3 the two shafts 32 and 33 are spaced from and parallel to each other. The shaft 33 is pivotally connected to a double armed lever or summarizing member 33 which is movable by stems 43 and 4I shown as provided with rollers 42 and 43 bearing against cams 44 and 43. 'I'he cam 44 is movable by means of a pressure responsive device shown as a bellows 43 communicating with the conduit 33 through a pipe 41. The second cam is movable by a temperature responsive device shown as a bellows 43 communicating with a thermostatic bulb 43 containing a fluid which expands and contracts in response to changes in temperature of the gas in the conduit 33. A compression spring 30 tends to maintain the rollers 42 and 43 in contact with the respective cams.

The operation of the device is as follows: Upon an increase in pressure of the gas to be measured the bellows 43 will move the cam 44 to the right, thereby moving the shaft 33 with the friction wheel upwardly and increasing the speed-ratio between the meter shaft 32 and the indicator shaft 33. An increase in temperature causes the bellows 43 to move the shaft 33 and friction wheel 34 downwardly, thereby diminishing the speed-ratio between the shafts 32 and 33. The indication of the counter 33 is therefore automatically corrected in response to changes in temperature and pressure of the gas, or. in other words, in response to changes in density of the gas, which is expressed as the ratio of absolute pressure to absolute temperature.

The means for displacing the ratio varying device. or ratio slider, may assume various forms. A preferred and very simple form is diagrammaticaily shown in Figure 4 in connection with a device for regulating a constant weight flow of gas.

A gas conduit 3I is equipped with a flow-responsive device shown as being a constriction 32 and a diaphragm casing 33 containing a diaphragm 34 acted upon by the differential pressure across the constriction 32. 'I'he diaphragm 34 controls a relay shown as being of the well known Askania" jet-pipe type. A .iet-pipe 33 is pivotally mounted about an axis 33 and supplied with pressure iluid from a suitable source (not shown). The fluid jet emerging from the jet-pipe nozzle enters receiving orinces 31 and 33 depending upon the relative position of the nozzle and the orifices, thereby setting up a difl'erential pressure in the pipes 33 and 33 leading to u opposite sides of a servo-motor piston 8| movable in a cylinder 62 and connected to operate a flow varying device shown as being a butterfly valve 63. A ratio lever Il is pivotally mounted about an axis 65 being spaced from and parallel to the axis 56 of a jet-pipe 55. The ratio lever 64 is acted upon by a force acting in opposition to the controlling force and shown as being a spring 66 adjustable by means of a stem 81 held in place by a set-screw 88. The ratio slider 89 is movable by means of a threaded shaft 10 having a head 1| of suitable cross section to prevent the same from turning. The threaded shaft engages a nut or summarizing member 12 rotatable by means of a hand wheel 13. A bearing 14 prevents the nut from moving axially. The nut is also connected to operate an indicating device by any suitable means, such as a belt orsprocket chain 15 trained on a pair of pulleys or sprockets 16 to rotate a graduated arm or pointer 11 relative to a scale or dial 18. In this instance, the pointer is removably and adjustably secured `to the end of an indicator shaft 19 operated by said pulleys or sprockets. The dial and pointer are shown on an enlarged scale in Fig. 5. The dial 18 carries a plurality of curves representing temperature degrees; while the pointer 11 is calibrated in terms of pressure. In the position shown, the device is set for a temperature of 60 F. at a pressure of 30.9 inches of mercury column. The calibrations and the arrangement are such that the nut 12 moves the shaft 69 by an amount representing the sum of the logarithms of the temperature and pressure correction factors.

The operation of the controlling device is as follows: 'I'he jet-pipe relay tends to maintain a constant differential pressure across the constriction 52 and thereby a constant flow through the conduit 5| by operating the valve 63. Upon an increase of flow, the flow responsive device will move the jet-pipe to the left, thereby causing the servo-motor 6|, 62 to move the valve 63 towards its closed position. The magnitude of the differential pressure is determined by the adjustment of the restoring spring 66. Upon a change of density of the gas caused by a change in temperature or pressure, theposition of th'e ratio slider is adjusted by means of the hand wheel 13 for the new temperature and pressure values whereby the controlling device permits a corrected volume of gas per time unit to pass through the conduit and the constant weight flow per time unit is maintained.

A different form of indicating device, more particularly for use in a combustion regulator, is shown in Fig. 6. The purpose of a combustion regulator is to supply a furnace with a constant amount of combustion air per quantity unit of fuel. Since the density of the air changes with the temperature a correction is introduced into the regulator to compensate for temperature changes and maintain a constant weight of air per quantity unit of the fuel in a predeterminable ratio. It may be assumed that the supply of fuel is independently maintained constant. The stationary dial 18 is calibrated in terms of ratio of air to fuel. The chain drive 15 moves an indicator shaft 19" carrying a small dial 80 which is secured thereto. A double pointer 8| is adjustable with respect to the small temperature dial 80 by means of a screw 82 and its long hand coacts with the large dial 18'. It may be assumed as an example that the regulator should be set for 120 F. and 10% excess. Starting with the pointer 8| on 60 F. as shown in Fig. 6, the hand wheel 13 (see Figs. 4 and 5) will be turned until the pointer reaches 10% excess indicated by the dial 18 having a logarithmic graduation. UDO-n this turning movement the pointer 8| will not be displaced relatively to the small dial 80 having likewise a logarithmic graduation. After this first adjustment in accordance with the logarithm of one of the correction factors the pointer 8| Will be disconnected from the shaft 19' by loosening of screw 82 and the pointer will be turned counter-clockwise from 60 to 120 F. and fastened again to the shaft. By this second displacement the pointer will also be displaced relatively tothe stationary dial 18 so that the pointer will not show any longer 10% but less.

Therefore, a second turning movement of the pointer and of the shaft is to be added in accordance with the logarithm of a second correction factor which will bring the pointer back to 10% excess.

From the foregoing, it follows that the slider 69 (see Fig. 4) will be displaced by a movement which is proportional to the sum of the logarithms of a plurality of correction factors, one of these factors being the temperature indicated by the small dial 80 and the other correction factor being the fuel air ratio or the excess indicated by the dial 12. The construction of the regulator may in all other respects be identical with the one shown in Fig. 4. The stationary dial 18 is provided with a logarithmic graduation. Likewise the small dial 80 carries a logarithmic graduation so that by adjusting the pointer 8| with respect to the small dial 8U and to the stationary dial 18 by means of the hand Wheel 13 (see Figs. 4 and 5) the ratio slider 69 will be displaced in proportion to the algebraic sum of the logarithms of the two correction factors `represented by the dials 18 and 8|II.Y

The present invention is not restricted to the particular embodiments thereof herein shown and described. Moreover, it is not indispensable that all the features of the invention be used conjointly, since they may be employed advantageously in various combinations and sub-combinations.

What is claimed is:

1. In a mechanical movement device of the class described having a pair of movable members, said members being mounted to move about parallel axes, and having oppositely directed portions, a single ratio slider engaging the oppositely directed portions of said members to vary the movement of one member relative to the other member, a summarizing member connected to said slider for displacing it relative to said movable members, and separate means for adjusting said summarizing member relative to a plurality of correction factors by an amount which is proportional to the algebraic sum of the logarithms of the correction factors to thereby vary the ratio of the movements of said movable members by an amount which, expressed as a function of the movement of said slider, approximates an exponential value of the movement of said slider.

2. In a mechanical movement device of the member, a summarizing member connected to said slider for displacing it relative to said movable members, and separate means for adJusting said summarizing member relative to a plurality of correction factors by an amount which is proportional to the algebraic aum of the logarithms of the correction factors to thereby vary the ratio of the movements of said movable members by an amount which. expressed as a function 0f the movement of said slider, approximates an exponential value of the movement of said slider.

3. A mechanical movement according to claim 1. in which the movable members consistV of a pair of lever members pivoted about spaced parallel axes of which the axis of one lever is oppo site the axis of the other lever.

4. A mechanical movement according to claim l, in which the movable members are in the form of a pair of spaced and parallel disks rotatable on axes which are parallel to each other, and in which the ratio slider includes a friction wheel engaging both side faces of and arranged in the space between the disks.

5. A mechanical movement according to claim 1, in which the movable members consist of a pivoted lever and a Jet pipe pivoted at one end,

said lever and let pipe being spaced from each other and between which the slider operates and the pivot points of the lever and Jet pipe being in opposito relationship.

8. A mechanical movement for the purpose dsl scribed comprising at least two movable members spaced from each other, said members being mounted to move about parallel axes, and having oppositely directed portions, a bridging member in constant contact with the oppositely dil0 rected portions of, and slidable in the space between, the two movable members; a summariaing member connected to said bridging member for displacing it between said movable members: and two separate means each independent- 15 1y operable relative to the other for adjusting said summarizing member relative to a plurality of correction factors by an amount which is pro portional to the algebraic sum of the logarithms of the correction factors to thereby vary the 20 ratio of the movements of said movable members by an amount which, expressed as a function of the movement of said slider, approximates an exponental value oi' the movement of said slider.

25 HERBERT'- ZIEBOLZ. HUBERT J. VELTEN. 

